The water in the Cannon Office Building on Capitol Hill was last tested for lead in September — and staffers for the House of Representatives might have been drinking contaminated water since then, according to a notice sent to chiefs of staff late Wednesday.

"We continue our investigation into the source of the lead situation in the Cannon House Office Building, and although we don’t have all the answers yet, we wanted to get more specific information to you as we received it," Mamie Bittner, a spokeswoman for Architect of the Capitol's Office, said in the notice.

The document, which also sought to address "frequently asked questions" on the situation, was obtained by Politico.

"We will continue to provide bottled water in the Cannon House Office Building until we have identified and resolved the problem," Bittner said.

Her office sent the notice amid questions from House staffers after disclosures Tuesday that lead levels in drinking water in the Cannon Office Building were "slightly above" EPA safety standards.

According to the notice, the September tests found that the water came up clean.

It said that EPA safety standards require that water in the building should contain under 15 parts-per-billion of lead, but the Architect's Office found that five out of 26 drinking water areas sampled had 17, 18, 20, 25 and 56 parts-per-billion.

That’s a 20 percent contamination rate, with the 56 reading being more than three times the safety limit, according to the Politico report.

However, in the initial disclosure on Tuesday, the office did not say when the water was last tested. It also did not specify how high the lead levels were — or provide advice on testing for lead poisoning.

His wife heads the staff of Arizona GOP Rep. Paul Gosar. She just gave birth last week and has been drinking the water in the Cannon Building throughout her pregnancy, Politico reports.

"These FAQ's are insufficient and seemingly purposefully vague," Foti wrote in an email to the Architect's Office that he provided to Politico Wednesday. "When was the most recent testing done and what period does it cover?

"How often are these tests done, specifically? When was the last test prior to this one conducted and what were the results? What does 'slightly above' EPA safe standards mean?

"Specifically, how much above were they? ... Do we all need to get tested for lead poisoning?" Foti asked.

After Tuesday's disclosure, staffers of Democratic Rep. Dan Kildee of Michigan sent Politico a statement bashing Republicans for not protecting those affected by poisoned water.

Kildee represents Flint, Mich., which has been coping with a serious lead-contamination problem since last year.

"Congress has so far failed to act on Flint aid and now some members of Congress have had their own water shut off due to high lead levels in their Washington offices," the statement said. "Lead is a dangerous neurotoxin and high levels of lead in water anywhere is a public health emergency.

"It is long past time that Congress get serious about this health threat," the statement continued. "Helping Flint families ought to be as much of a priority as ensuring safe water on Capitol Hill."

The water in the Cannon Office Building on Capitol Hill was last tested for lead in September — and staffers for the House of Representatives might have been drinking contaminated water since then, according to a notice sent to chiefs of staff late Wednesday.